Table 3.

Piezoelectric stress coefficients $e_{ij}$ for pristine GeS, GeS with vacancies (${\mathrm{V}}_{\mathrm{Ge}}$, ${\mathrm{V}}_{\mathrm{S}}$), and GeS with substitutional atoms (${\mathrm{Sn}}_{\mathrm{Ge}}$, ${\mathrm{Se}}_{\mathrm{S}}$) compared with previous studies for pristine GeS and ${\mathrm{MoS}}_2$.

	Pristine GeS	${\mathbf{V}}_{\mathbf{G}\mathbf{e}}$	${\mathbf{V}}_{\mathbf{S}}$	$\mathbf{S}{\mathbf{n}}_{\mathbf{G}\mathbf{e}}$	$\mathbf{S}{\mathbf{e}}_{\mathbf{S}}$	Pristine GeS [33]/[34]	$\mathbf{M}\mathbf{o}{\mathbf{S}}_2$
$e_{11}\left(C/Å\right)$	5.84	7.92	5.72	5.94	5.83	7.28/4.6	3.66/3.64 [53]
$e_{12}\left(C/Å\right)$	−4.59	−8.29	−3.67	−4.36	−4.51	−4.97/−10.1	−3.67/−3.64 [53]